Different stages of B cell differentiation in non-T acute lymphoblastic leukemia

An in situ study of CD34(+) cells in human fetal bone marrow

The purpose of this study was to characterize the spatial distribution, number and size of CD34(+) cells in fetal bone marrow. Thin sections of normal fetal bone marrow from lumbar vertebrae were stained using CD34 antibody QBend/10. Sections were used under light microscopy with various eyepiece graticules to make measurements of CD34(+) cells in situ. Results showed that at mid- and late gestation, approximately 2% and 0.5% of fetal bone marrow cells were CD34(+) respectively. The mean distance of CD34(+) cells from the nearest trabecular bone surface was 61 +/- 4 and 46 +/- 4 microm, respectively, for mid- and late gestation. The mean distance to the nearest neighbour was 46 +/- 5 and 105 +/- 15 microm, and the mean distance to the nearest blood vessel was 13 +/- 1 and 17 +/- 2 microm respectively. The concentration of CD34(+) cells in the peripheral region was 6.5 times greater than that at the centre of the sections. Overall, the percentage number of CD34(+) cells decreased with gestational age. The cellular and nuclear diameters of CD34(+) cells remained unchanged throughout mid- and late gestation at 5.4 +/- 0.1 and 3.8 +/- 0.1 microm respectively. This information will be used to calculate the natural background alpha-radiation dose to haemopoietic stem cells.

Biology and treatment of adult acute lymphoblastic leukemia

The molecular analysis of acute lymphoblastic leukemia (ALL) has provided exciting insights into the pathogenesis of this disease. This disease is heterogenous and can be subtyped based on chromosomal, immunophenotypic, and structural criteria. The varying prognostic implications of different ALL subtypes markedly influence the treatment decisions in adults. Many patients with T-cell ALL can be cured with chemotherapy alone. In contrast, patients with early B-lineage ALL with certain chromosomal abnormalities, especially the Philadelphia chromosome, do not have durable responses to chemotherapy and should receive a bone marrow transplantation if an HLA-matched donor is available. Recent reports have shown improved results for adults with B-cell ALL (Burkitt's) after intensive alternating cycles of chemotherapy containing high doses of methotrexate and cyclophosphamide. Future clinical and laboratory investigation should lead to the development of novel and possibly more effective treatments specifically tailored for different subsets of ALL.

A correlation between the expression of the bcr-abl chimeric gene and severity of the clinical state of CML patients with time

Using the reverse polymerase chain reaction, four Ph' positive CML patients were followed for 2 years; a correlation between the severity of the clinical state and the b3a2 expression was noted with time. Additionally, amplification of the c-myc proto-oncogene was observed, using Southern blot analysis, in one patient prior to his entry to the blast phase. No reorganization of the bcr-abl rearrangement site was found in the latter patient. The data suggest that a routine follow-up of CML patients using the Southern blot analysis and the reverse transcription-polymerase chain reaction might be of importance in evaluating the progression of the disease.

Molecular analysis of an asymptomatic Ph-positive CML patient with 27 years of prolonged remission

We describe the results of clinical, cytogenetic, and molecular biological studies of a patient who, after two courses of treatment with Busulphan, has remained free of symptoms of Philadelphia chromosome-positive chronic myeloid leukemia for 27 years, except for the persistence of a Ph1 chromosome and the presence of its transcribed chimeric mRNA.

Genetic changes: relevance for diagnosis and detection of minimal residual disease in acute lymphoblastic leukaemia

Cure can now be achieved in a proportion of patients with ALL. However, relapse and eventual treatment failure occur in many cases receiving identical treatment, presumably as a result of failure to eradicate MRD. While for many years marrow morphology has been the standard by which leukaemic remission has been assessed, more sensitive techniques have been developed for detection of MRD including immunophenotypic analysis, and as discussed in this chapter, methods which detect leukemia-associated clonal genetic changes at the karyotypic and genomic levels. Table 10 lists the applicability and sensitivity of various markers used in MRD analysis in ALL. It is apparent that of the karyotypic and molecular approaches described, only PCR-based strategies for detection of either leukaemia-specific translocations or clonal Ag receptor rearrangements are reliably applicable to a high proportion of both B- and T-ALL at sufficiently high sensitivity. Initial clinical studies of patients undergoing therapy for ALL using a variety of PCR-based methods suggest that in some cases a persistent or increasing level of residual disease may be predictive for clinical relapse, although a number of technical factors and the phenomena of oligo-clonality and clonal evolution may limit the usefulness of this analysis in a few instances. From current available data it appears that in order to define the potential predictive value of PCR detection of MRD a large number of patients will need to be prospectively assessed over several years at multiple time points during and after therapy, preferably using more than one semi-quantitative PCR approach. In addition to reliable prediction of clinical relapse allowing appropriate individual treatment modification, progress in the molecular detection of MRD in ALL is also likely to be of benefit in the assessment of the efficacy of autograft purging and the evaluation of new therapeutic strategies such as the use of biological response modifiers to eliminate a low tumour burden.

Analysis of rearranged immunoglobulin genes indicating a process of clonal evolution in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is known to be a stable monoclonal neoplasm. In contrast to early studies demonstrating no more than two hybridizing immunoglobulin heavy chain bands corresponding to the two expected alleles, we have demonstrated an unexpected multiband pattern when the HindIII-digested DNA samples from 38 CLL patients were analysed by Southern blot hybridization using JH and C mu gene probes. In order to characterize the genetic basis for the multiband pattern, we molecularly cloned the immunoglobulin heavy chain genes of one of the patients whose leukaemic DNA sample demonstrated three hybridizing JH bands and a loss of the germline band. The cloned rearranged immunoglobulin genes could be divided, based on the restriction mapping and the hybridization with the various probes, into two basic patterns representing two alleles. In one of the cloned rearranged immunoglobulin genes a secondary rearrangement occurred that resulted in the addition of 300 base-pair long sequence into the switch region, and the creation of a HindIII restriction site. The results of the study suggest that clonal evolution occurs in some CLL, and that many of these neoplasms are indeed oligoclonal due to the accumulation of secondary genetic changes.

Cytogenetic rearrangement of C-MYC oncogene occurs prior to infection with Epstein-Barr virus in the monoclonal malignant B cells from an AIDS patient

Two cell lines were originated from the peripheral blood (PB-LAM) and bone-marrow (BM-LAM) of a patient with Burkitt-type acute lymphoblastic leukemia and AIDS. 26 and 7 clones were isolated from PB-LAM and BM-LAM respectively by limiting dilution. All of these had surface IgM lambda and the CD10 marker with low to absent CD23, CD30, CD39 and surface adhesion molecules. Furthermore, they shared the same chromosomal abnormalities (trisomy 7 and t(8;14) translocation) and the same rearrangements of immunoglobulin L and H chain and of c-myc gene loci. These features are those most frequently found in Burkitt's lymphoma (BL) cells and were different from those of the parental cell lines, which, besides cells identical to those of the malignant clones, also contained normal lymphoblastoid cells. Therefore, the cloning procedure used selected for the growth of cells with malignant features. EBV latent antigens were detected in all clones by Western blotting and their pattern of expression resembled that usually observed in BL cells. All the clones were positive for the EBV genome by Southern blotting and had monomorphic EBV-fused termini as determined by using cDNA probes specific for sequences at either end of the viral genome. However, the clones derived from PB-LAM had EBV fused termini of a different size from that of the clones derived from BM-LAM. The presence of different EBV-fused termini in otherwise monoclonal malignant cells indicate that EBV infection was possibly a late event in lymphomagenesis following rearrangement of the c-myc and the Ig gene loci.

Karyotype evolution in a patient with biphenotypic neonatal leukemia

We present the case of a 4-day-old boy with acute lymphoblastic leukemia showing at onset a karyotype 46,XY,t(4;11)(q21;q23). At relapse an additional change, add(2), was present. Molecular analysis showed the same immunoglobulin rearrangement both at onset and at relapse, but immunohistochemical analysis revealed some cells having myeloid features. A continuous cell line derived from the leukemic blasts of the patient presented typical monoblastic features.

Phenotypic and genotypic switch in Philadelphia-positive, BCR-positive blast crisis of chronic myeloid leukemia

We report a case of Ph1-positive, bcr-positive chronic myeloid leukemia blast crisis (CML-BC) which at presentation showed a mixed myeloid/B-lymphoid immunophenotype along with TdT positivity and, at the molecular level, an oligoclonal rearrangement of the immunoglobulin heavy chain (IgH) gene region. After obtaining a successful remission, at the time of relapse the patient underwent a phenotypic and genotypic switch from mixed to myeloid phenotype, characterized by the loss of the lymphoid markers and TdT expression and by a germline configuration of the IgH gene region. The same bcr rearrangement was, however, found in both phases of the disease, supporting the suggestion of a true phenotypic and genotypic conversion. This report confirms that the neoplastic event in CML may take place at an early multipotent stem-cell level, prior to a well-defined phenotypic and genotypic lineage expression. Moreover, it is suggested that different factors (chemotherapy? growth factors?) may have either eradicated the bcr+/IgH+ clone and promoted the growth of bcr+/IgH- leukemic cells or, alternatively, supported the lymphoid differentiation program and induced a myeloid lineage shift.

Unique genotypic features of infant acute lymphoblastic leukaemia at presentation and at relapse

Acute lymphoblastic leukaemia (ALL) of infants aged less than 1 year represents a group of patients with peculiar biological features, poor response to therapy and unfavourable prognosis. In order better to characterize this type of leukaemia, we have investigated the immunoglobulin (Ig) and T-cell receptor (TCR) genes configuration of 21 infants with ALL, and compared the genotypic features with the phenotypic and karyotypic data, as well as with the clinical outcome. All cases had a pre-B phenotype; 12 (57%) of them were pre-pre-B ALL (CD10-, CD19+). Six of the 16 cases evaluated (38%) displayed chromosomal abnormalities; five had the typical translocation t(4;11)(q21;23). Eleven cases presented with a white blood cell count greater than 100 x 10(9)/l. The clinical course was unfavourable in 14 patients. The genotype of this group of ALL revealed several peculiarities. (1) Of the 21 cases, six (29%) displayed a multiple rearrangement pattern at the IgH locus. (2) In three cases (15%), the light chain genes were rearranged. (3) The TCR beta and gamma genes were rearranged in only one case (one case at the TCR beta and one at the TCR gamma locus). (4) The TCR delta chain was rearranged in eight cases (40%) and rarely deleted; the rearrangements observed were those most frequently observed in B cell-precursor ALL. Two cases were evaluated both at presentation and at relapse. While the immunophenotype had remained unmodified, comparison of Ig heavy chain gene rearrangements revealed clonal variations in both cases. Taken together, these findings further underline the biological peculiarities of infant ALL compared to ALL which occurs in older children and in adults, and stress the need of differentiated and aggressive therapeutic approach for these patients.

A human lymphoma cell line with multiple immunoglobulin rearrangements

The development of a cell culture system efficient in the establishment of lymphoma cell lines has made it possible to dissect basic biological and molecular aspects of lymphoma cells. We have established a lymphoma cell line from a patient with B cell lymphoma. The cell line has a complex karyotype with translocations involving bands 8q24, 14q32, and 18q21. Molecular analysis revealed that the Myc gene was rearranged; we were unable to demonstrate rearrangement of the Bcl-2 gene. Evaluation of the structure of the heavy chain Ig genes revealed that the cell line carried the same rearrangements as the cells from which the cell line was derived. The pattern of rearrangement, however, was unusual in that there were at least four rearranged bands when DNA cut with HindIII was probed with a fragment of the heavy chain joining region. To further characterize the cell line, subclones were derived. Individual subclones had the same pattern of rearrangement as the parent cell line. The results of these studies provide evidence that multiple rearranged Ig genes may be present in a single clone of cells.

Presence of more than two rearranged immunoglobulin heavy-chain genes in adult precursor B-cell acute lymphoblastic leukemia

We examined the configuration of the immunoglobulin genes in the leukemic blast cell DNA of 20 adults with precursor B-cell acute lymphoblastic leukemia (ALL), treated according to the BMFT protocol. Sixteen of 20 (80%) patients expressed HLA-DR antigens and lacked detectable T-cell antigens. Eleven of the 20 patients (55%) were positive for the CD10 antigen and therefore classified as common ALL. Six patients were classified by immunological phenotyping as null-ALL (30%). Three patients (15%) expressed both immature B-cell markers CD19, CD22, or CD24 and myelomonocytic markers CDw65 or CD15, suggesting precursor B-ALL with cross-lineage expression of myeloid markers. In 18 of the 20 patients (90%), rearrangements and/or deletions of the immunoglobulin heavy-chain (IgH) gene locus were found. In none of the patients was a light-chain gene rearrangement observed. Two patients (10%) had a rearrangement of one allele for the J beta 1 gene region of the TCR-beta gene. In four patients (20%) more than two hybridizing bands for the IgH genes were detected. Two of these four patients with multiple hybridizing bands for the IgH genes had a t (4;11) translocation. Two of five patients with the t (4;11) translocation co-expressed both B-cell antigens and the myeloid antigens CD15 or CDw65. No correlation was found between the immunophenotype of the ALL and the arrangement pattern of their IgH genes. Kaplan-Meier plot analysis revealed no significant difference between adult precursor B-ALL patients with monoclonal or oligoclonal IgH gene rearrangements and their disease-free survival rates.

Clonally expanded CD3+, CD4-, CD8- cells bearing the alpha/beta or the gamma/delta T-cell receptor in patients with the lymphoproliferative disease of granular lymphocytes

Among 60 retrospectively assessed patients with the lymphoproliferative disease of granular lymphocytes (LDGL), lymphocytes from only 2 patients had the CD3+, CD4-, CD8- phenotype, rarely observed in normal peripheral blood lymphocytes (about 3%). In this paper we report a detailed study of lymphocytes isolated from these two patients. The cells from patients 1 had the CD3+, CD4-, CD8-, WT31-, beta F1-, TCR delta 1+, Ti gamma A-, BB3+, CD7+, CD16-, CD57+ phenotype, while cells from patient 2 had a phenotype even more rarely observed on normal lymphocytes: CD3+, CD4-, CD8-, WT31+, beta F1+, TCR delta 1-, CD7+, CD16-, CD57+. Thus, in only the first case the cells expressed the gamma/delta T-cell receptor (TCR) on the membrane, while the cells from the second case had the alpha/beta TCR. Genetic studies showed that in case 1 the TCR gamma gene was rearranged and the beta chain gene configuration was germline; the TCR mRNA was of normal size for the gamma chain, while that of the beta chain was truncated. Case 2 had the beta and the gamma genes of the TCR rearranged, but only the alpha and beta mRNA were expressed. In agreement with these findings, the delta chain gene of the TCR was rearranged in case 1 and was deleted in case 2. Cytotoxic activity was absent in cells from case 1 and low in case 2; in the latter, the lytic activity could be up-regulated following incubation with IL-2 or an anti-CD3 monoclonal antibody. Our study indicates that CD3+, CD4-, CD8- lymphocytes are rarely expanded in patients with LDGL. The detection of a lymphoproliferative disease of a CD3+, CD4-, CD8-, alpha/beta + cell may contribute to a better characterization of this novel lymphocytic subpopulation.

The molecular genetic analysis of gene rearrangements in acute lymphoblastic leukaemia

In ALL the majority of cases possess clonal rearrangements of the Ig or TCR gene loci. Detection of these clonal markers by Southern blot analysis over a disease course has provided information on the fate and origin of leukaemic clones during treatment. Detection of these gene rearrangements has been used to detect residual disease during treatment. More recently, methods have been developed for the detection of Ig and TCR gene rearrangements using the polymerase chain reaction (PCR). This amplification technique allows for the rapid detection of gene rearrangements with a greater sensitivity than more conventional methods. The full impact and usefulness of this technique in residual disease detection has yet to be determined. The presence of the Philadelphia chromosome t(9;22) in ALL is associated with poor prognosis. Its detection by Southern blot is technically complicated due to the heterogeneity of chromosome breakpoints involved. The development of PCR-based methods for the detection of the bcr/abl mRNA associated with the Philadelphia chromosome has improved our understanding of the significance and incidence of this disease marker in ALL, emphasizing the importance of establishing Philadelphia status on all patients at diagnosis. Although longitudinal studies in CML have shown the presence of bcr/abl mRNA to be associated with residual disease, and its absence associated with long-term remission, these studies have yet to be reported for ALL. The usefulness of detection of residual disease using bcr/abl has yet to be determined.

Kappa light chain gene rearrangement in a T-cell lymphoma

Forty-three patients were studied to determine whether light chain gene rearrangements may occur in hematopoietic cells not pertaining to the B-lineage. In only one patient, affected by T-cell lymphoblastic lymphoma, one kappa light chain allele was rearranged. Neither at the protein level nor at the RNA level the rearranged gene was expressed. These data confirm that, although rarely, kappa light chain gene rearrangements may occur in neoplastic T-cells. Furthermore, as in our patient Ig heavy chain genes retained a germline configuration, the present data demonstrate that kappa light chain gene rearrangements may occur regardless of Ig heavy chain gene arrangement.

Interleukin 2 does not promote the in vitro and in vivo proliferation and growth of human acute leukaemia cells of myeloid and lymphoid origin

The effect of recombinant interleukin 2 (IL2) on the in vitro and in vivo proliferation and growth of human acute leukaemia cells of both myeloid and lymphoid origin was investigated. In none of the 25 primary samples tested could a continuously in vitro growing cell line be obtained by adding IL2 to the culture medium. Although IL2 induced a proliferative signal in three of the 31 acute leukaemias analysed, the overall 3H-thymidine uptake of the neoplastic cells was significantly reduced (P less than 0.05) in the presence of IL2. The unlikelihood of an important proliferative signal triggered by IL2 was confirmed in a semisolid clonogenic assay, which failed to document an increased colony growth in the 26 samples studied. Furthermore, using a colorimetric assay as a test for cell proliferation and survival, in seven of the 11 fresh acute leukaemia samples tested a 22-40% reduction in viability was observed in the presence of IL2, while in the remaining four, IL2 was ineffective. In order to investigate the effect of IL2 in an in vivo setting, an experimental model in heavily immunosuppressed nu/nu mice was established. In no case did IL2 promote the in vivo proliferation and growth of human myeloid and lymphoid acute leukaemia cells injected in the mice. On the contrary, with seven of the eight leukaemic cell lines which gave rise spontaneously to leukaemic masses, this could be prevented when the mice received locally 300 U of IL2 three times daily for 90 d. IL2 also blocked the growth in vivo of three fresh acute leukaemia samples (two myeloid and one lymphoid). Co-culture experiments using leukaemic cell lines and increasing numbers of normal lymphocytes suggest that the inhibitory effect of IL2 is probably exerted via an indirect mechanism. These findings, coupled to the well-documented ability of IL2 to generate lymphokine activated killer cells cytolytic against leukaemic blasts, further point to the potential role of immunotherapy with IL2 in the management of patients with haematological malignancies.

Oligoclonal immunoglobulin gene rearrangements in Philadelphia chromosome-positive common acute lymphoblastic leukemia

The occurrence of more than two rearranged bands of immunoglobulin heavy chain (IgH) genes in B precursor acute lymphoblastic leukemia (ALL) has recently been documented. To elucidate the nature of such leukemias, we studied 30 patients with common ALL, including 6 patients with Philadelphia chromosome (Ph1)-positive ALL, by immunophenotyping and genotyping. In 10 of the 30, Southern blotting showed oligoclonal patterns of IgH gene arrangements, which were frequently detected in Ph1-positive ALL. In one patient of the 10, three rearranged bands of Ig kappa chain genes were detected. Ph1 abnormality and co-expression of myeloid associated antigens were found in 5 and 5 of the 10, respectively. Detection of multiple fragments of IgH genes would be suggestive of multipotent progenitor origin of these ALL.

Establishment of an EBV-positive lymphoblastoid cell line that grows as a lymphoma in nude mice and expresses membrane CD2 molecules

We describe a human lymphoblastoid cell line (LCL), called ZS, that originated spontaneously from the cultures of gamma-irradiated (50 Gy) peripheral-blood mononuclear cells of a normal donor. When injected subcutaneously in sublethally irradiated, splenectomized and anti-asialo-GM1-treated nude mice, ZS cells invaded the lymph nodes, that appeared 10 to 50-fold enlarged in all of the mice tested. Furthermore, ZS cells expressed a typical T-cell surface structure, the CD2 molecule, detectable by a variety of different anti-CD2 monoclonal antibodies (MAbs). However, other T-cell markers were not found, with the possible exception of a truncated messenger of the beta chain of the T-cell receptor and ZS cells could be identified as B cells since they (i) expressed a battery of markers of the resting and activated B cells, (ii) displayed a monoclonal rearrangement of the IgH chain locus and (iii) synthesized IgM K molecules. The Epstein-Barr virus (EBV) genome was detected in ZS cells in approximately ten copies per cell by DNA hybridization techniques. Furthermore, the cells were positive for EBV nuclear antigens (EBNA). Western blotting analysis of EBV encoded antigens demonstrated clear differences with those present in the B 95.8 virus-producer cell line, indicating that ZS cells were not infected by EBV in vitro and that they already harbored the virus in vivo. ZS cells formed colonies in vitro with a high cloning efficiency and displayed chromosomal abnormalities in all of the mitoses (karyotype 47, xy, +13, -14, 8p+, 21p+, +m). In spite of these malignant features, ZS cells expressed the full range of EBV latent proteins as usually do "normal" LCSs and did not have any of the chromosomal abnormalities that juxtapose the c-myc oncogene to one of the genes coding for immunoglobulin molecules.

Immunoglobulin DNA Analysis as a Marker of Clonality in the Follow-up of Patients with Hairy Cell Leukemia Treated with Alpha-Interferon

In fourteen patients with hairy cell leukemia (HCL) the configuration of the immunoglobulin (Ig) heavy chain genes was used as a marker of clonality, to monitor the response of the neoplastic population to treatment with alpha-interferon (a-IFN). In agreement with the morphological, hematological and immunological data, twelve of them showed, after a variable length of therapy, a complete disappearance of rearranged bands in peripheral blood cells. In one patient, who was treated less intensively, the molecularly-defined neoplastic population was still present on two consecutive determinations, whilst in the last patient persistence of disease was repeatedly documented despite prolonged A-IFN treatment. Three further cases were analyzed sequentially: in two, no rearranged bands could be found at repeated determinations; the third, who was in complete remission whilst on 3 × 10(6) U of α-IFN every other day, showed recurrence of disease nine months later when on a maintenance protocol with 3 × 10(6) U/weekly. Nine bone marrow specimens were also analyzed following treatment with α-IFN. In four a monoclonally rearranged band could still be detected, while in another four, reversal of fibrosis and hemopoietic recovery wits coupled with the absence of a molecularly recognizable neoplastic clone. In the last (case, persistence of disease paralleled the findings in the peripheral blood cells. These data indicate that α-IFPJ is capable of producing a specific cytolytic effect on the leukemic population in HCL, which in some cases may lead to complete clonal remissions. Analysis at the DNA level may represent a valuable tool towards monitoring the clinical course of HCL patients and for optimal individual therapeutic scheduling.

Genetic heterogeneity in blast crisis of chronic myelocytic leukemia

Fourteen patients with lymphoid and mixed blast crisis (BC) of chronic myelocytic leukemia were studied by immunophenotyping and genotyping. Rearrangements of immunoglobulin heavy chain (IgH), T-cell receptor (TcR) gamma and TcR beta genes were detected in all 14, in nine and in four patients, respectively. Interestingly, more than two rearranged bands of IgH gene in three lymphoid BC and two rearranged bands with germ line band in 1 biphenotypic BC indicated the genetic heterogeneity of the blasts. Some blastic transformations are thought to occur at a more immature stage of hematopoietic differentiation than that indicated by the phenotype and genotype of BC cells.

Immunoglobulin heavy chain gene rearrangements in chronic lymphocytic leukaemia: correlation with clinical stage

A search for a correlation between the clinical stage of chronic lymphocytic leukaemia (CLL) and the pattern of immunoglobulin heavy chain gene rearrangements was undertaken. DNA samples from the leukaemic cells of 38 CLL patients were analysed by Southern blot hybridization. Using probes for the immunoglobulin heavy chain J (JH) and C mu regions a marked heterogeneity of the hybridization patterns was observed in both regions. The number of JH hybridization bands varied from one to four and more than two were found in 58% of the patients. In 42% of the patients no germline JH genes were found. One to three additional C mu bands were observed in 34%, but the germline was preserved in all samples. There was no correlation between the clinical stage and the number of hybridizing JH bands; however, a significant correlation was found between the loss of JH germline band or a C mu multiband pattern and advanced stage of the disease. The genetic events in the immunoglobulin genes observed in advanced CLL patients are assumed to result from clonal evolution and tumour progression.

Detection of minimal disease in hematopoietic malignancies of the B-cell lineage by using third-complementarity-determining region (CDR-III)-specific probes

Approximately 80% of hematopoietic malignancies of the B-cell lineage carry only one or two immunoglobulin heavy chain gene rearrangements indicating their clonal origin. These rearrangements due to the recombination of various variable, diversity, and joining regions of the heavy-chain gene segments during B-cell commitment result in a region called complementarity-determining region III (CDR-III). This region, which encompasses the diversity region of the heavy-chain segment, because of extensive somatic mutations, provides a DNA-encoded signature specific for each B-cell clone. CDR-III sequences were obtained from DNA of pre-B-cell acute lymphoblastic leukemia by using suitable primers and the polymerase chain reaction. The sequences were used to generate diagnostic probes that hybridized only to the amplified CDR-III of leukemic cells from which the sequences were derived. With these probes, leukemic cells could be detected when diluted 1:10,000 with other cells. By cloning the amplified CDR-III into recombinant libraries residual leukemic cells were accurately quantitated in bone-marrow samples from repeated relapses and remissions in one case of acute lymphoblastic leukemia. During a clinical remission lasting greater than 7 mo, malignant cells were present in marrow at greater than 1 per 1000 cells. These findings indicate that custom-made diagnostic probes will be useful in accurate quantitation of malignant cells in acute lymphoblastic leukemia patients in clinical remission and will allow investigation of the biological significance of low or high numbers of residual leukemic cells in evolution of that disease.

Investigation of the CD10 (cALLA) negative acute lymphoblastic leukaemia: further description of a group with a poor prognosis. French Groupe d'Etude Immunologique des Leucémies

The absence of CD10 (cALLA) in non-T non-B acute lymphoblastic leukaemia (ALL) is usually considered to be of adverse prognostic significance. From a large multicentre series of phenotyped ALL, we have identified a group of 23 non-T non-B ALL where blast cells were CD10 negative and CD19 positive. Class II antigens were present in 80% and C19 in 70%. Eight patients had successful karyotype analysis at diagnosis, and an additional patient at first relapse. Seven of these karyotypes showed a (4;11) (q21;q23) translocation. Most of the patients (70%) were young females, and they often presented with organomegaly. Six patients were less than 1 year old. The white cell count was over 100 x 10(9)/l in 48% of the cases. The FAB type was L2 in 56% of the patients. The most striking features were the poor response to therapy and survival. Six patients never attained complete remission and nine patients relapsed, most of them during the first year after diagnosis. Allogeneic bone marrow transplantation was performed in three children, of whom two are still alive 2 years after diagnosis. This study emphasizes the prognostic value of immuno-phenotypic and karyotypic investigations of ALL.

Immunologic and molecular evaluation of residual disease in B-cell chronic lymphocytic leukemia patients in clinical remission phase

This study evaluates residual disease in 28 B-cell chronic lymphocytic leukemia (B-CLL) patients who obtained a clinicohematologic remission after intensive chemotherapy. Sixteen of 28 patients (57%) showed a normal number of circulating B-lymphocytes, as demonstrated by the low percentage of mouse rosette-forming cells (M-RFC), surface immunoglobulins (SIg), and CD24-positive cells. Clinically, a lower number of relapses occurred in this group of patients compared to those with a persistent expansion of peripheral B-cells (P less than 0.05). In order to assess monoclonality of the residual peripheral B-cell population, the distribution of SIg light chains was investigated on the B-cell-enriched fraction of 15 of these 16 cases. Only six of them had a kappa/lambda ratio which ranged between 1.7:1 and 3:1, whereas the remaining patients still displayed a clearly imbalanced kappa/lambda Ig light chain distribution. On the other hand, the analysis of the configuration of the Ig heavy chain gene region, performed in nine cases (including five of the above six cases), showed the persistence of a rearranged pattern in all cases tested but one. Therefore, residual monoclonal B-cells were found also in the majority of cases which displayed the lowest kappa/lambda ratio, a normal bone marrow lymphocytosis and a long-lasting clinical remission. Studies at the DNA level confirm that a remission is rarely achieved in this disease in spite of intensive and prolonged chemotherapy. Nonetheless, the follow-up of B-CLL patients by conventional immunologic markers may be helpful to better define response to therapy and to predict the occurrence of clinical relapse.

Regulation of IgM biosynthesis in human chronic lymphocytic leukemia. Normal and neoplastic B cells respond differently to TPA

According to the pattern of IgM biosynthesis (membrane expression and secretion), human B cell chronic lymphocytic leukemias (B-CLLs) were subgrouped into four classes, namely: class I: membrane- secretion-; class II: membrane+ secretion-; class III: membrane+ secretion+; class IV: membrane- secretion+. Abundant membrane mu chain mRNA was present in cells from all cases, indicating that translational and/or post translational events were responsible for the absence of surface IgM in classes I and IV. Similarly, post translational events blocked IgM secretion in non secreting B-CLL cells. In B-CLLs from classes I, II and III, TPA induced IgM secretion by up-regulating secretory mu chain mRNA. By contrast, in normal B cells, TPA induced down-regulation of the secretory form of Ig mRNA, irrespective of the maturational stage of the cell. These observations indicate that IgM biosynthesis is modulated differently by TPA in normal and malignant B cells.

Molecular characterization of Ph' + hybrid acute leukemia

The configuration of the immunoglobulin heavy chain (IgH), T-cell receptor (TcR) beta and gamma chain regions, and the major breakpoint cluster region (M-bcr) genes were analysed in four cases of Ph' + acute leukemia (AL). Monoclonal rearrangements of the IgH region were detected in three cases exhibiting two phenotypically distinct cell populations (i.e. one lymphoid and one myeloid. In one of these cases, identical genetic events were observed by molecular analysis of FACS separated blasts. Multi-lineage rearrangements involving also the TcR gamma gene were observed in a biphenotypic AL showing co-expression of markers. The lack of rearrangements within the M-bcr gene, together with demonstration in one case of the Ph' + AL specific p190 protein product, pointed against the occurrence of chronic myeloid leukemias presenting in blastic transformation. Our results imply that such cases are to be considered as true AL and should therefore be included in the definition of hybrid AL.

Continuing rearrangement but absence of somatic hypermutation in immunoglobulin genes of human B cell precursor leukemia

Southern blot analyses revealed that cells from nearly 30% of childhood B cell precursor acute lymphoblastic leukemias (ALLs) contained more than two rearranged, nongermline bands for Ig heavy chain genes. DNA corresponding to these bands was molecularly cloned from two cases which showed three and seven rearranged bands, respectively. Nucleotide sequence analysis of the cloned DNA demonstrated that each band represented different VDJ or DJ rearrangements. While the same DJ joints were shared by several rearrangements, different DJ joints were found in the majority of rearrangements, precluding V region substitution as an explanation for the multiplicity of heavy chain rearrangements in these leukemias. Most of the V region segments involved in these rearrangements were restricted to VH region families that have been shown previously to be preferentially rearranged in human fetal B lineage cells. Sequence analysis of multiple copies of the same VDJ rearrangements from different cells revealed no somatic mutation, a mechanism responsible for detection of extra rearranged Ig DNA bands in certain other B lineage tumors. The data suggest that in some cases of ALL Ig heavy chain genes begin and continue to rearrange de novo within the neoplastic B cell precursor populations derived from an original malignant cell transformed at a stem cell stage of differentiation.

Incidence of lineage promiscuity in acute myeloblastic leukemia: diagnostic implications of immunoglobulin and T-cell receptor gene rearrangement analysis and immunological phenotyping

Sixty-nine blood or bone marrow samples from both children and adults with acute myeloblastic leukemia (AML) were investigated to elucidate the frequency of immunoglobulin (IG) and T-cell receptor (TCR)-gene rearrangements. Non-germline configuration for the IG heavy chain (h) gene was detected in the specimens of nine patients of various subtypes according to the French-American-British classification (FAB), including FAB M1, M2, M4 and M5. Rearrangement of the IG kappa chain (k) gene was present in one of these cases which simultaneously revealed a rearranged TCR-beta (b) chain gene. In another two AML samples we found TCR-b gene rearrangements, in one case in combination with an IG-h gene rearrangement. IG-h gene rearrangements were detected in 10 cases, in one case in conjunction with an IG-kappa (k) and TCR-b gene rearrangement. A highly significant correlation between the occurrence of DNA rearrangements of the IG-h locus and nuclear staining with the enzyme terminal deoxynucleotidyl transferase (TdT) and surface expression of the CD 19 and CD 34 antigen could be identified: all 10 TdT positive AML samples rearranged IG-h. Similarly, six out of 69 AML samples exhibited surface expression of CD 19, five of these in combination with CD 34 and all of them rearranged the IG-h gene. The one leukemia with TCR-b gene rearrangement only was TdT positive as well, but did not express CD 19 or CD 34. We conclude that IG-h gene is rearranged in a substantial proportion of AML, strongly associated with a specific immunophenotype (TdT+, CD19+, CD34+), whereas TCR-b gene rearrangement appears more rarely. No positive correlation between occurrence of IG-h and TCR-b gene-rearrangements and one AML FAB-subtype was found, although a clustering of M1 and M4 FAB subtypes in the AML group showing reconstructed IG-h gene became evident.

Multilineage cell involvement in Ph1-negative, bcr-negative chronic myeloid leukemia

We report a case of Ph1-negative, bcr-negative CML-BC, in which the primary leukemic cells displayed T-related antigens (CD7, CD4) in addition to HLA-DR and CD25 determinants. No B-lymphoid, myeloid and megakaryoblastic surface antigens were detected. In spite of this phenotype, DNA analysis revealed a germ-line configuration of the T-cell receptor beta chain gene region. Moreover, in-vitro culture studies demonstrated a proliferative response of the blast cell population to natural and recombinant myeloid-related factors, while no proliferative signal was observed in the presence of IL-2. The myeloid lineage was further demonstrated by the expression of myeloid-associated antigens on cultured blast cells, which still retained the CD7 antigen. Finally, cytogenetic analysis revealed a monosomy 7 which is usually associated with a stem cell leukemia. These results support the hypothesis that Ph1-negative, bcr-negative CML is characterized by the involvement of a multipotent stem cell capable of multilineage expression and indicate that differentiative and proliferative assays provide a further tool towards a more precise recognition of hematological disorders of uncertain origin.

Nonrandom TRG gamma variable gene rearrangement in normal human T cells and T cell leukemias

To estimate the extent of the TRG gamma variable (V) gene repertoire used in human T cell ontogeny, we have analyzed the variety of V gamma gene rearrangements in a large series of T and non-T acute and chronic leukemias. A limited heterogeneity of rearranged fragments was observed: only 13 types of differently rearranged fragments, four of which occurred only once, were found among 80 rearranged chromosomes. Furthermore, in the leukemic population as a whole, the frequency distribution of the most common types of rearranged V gamma gene-containing fragments appeared to be nonrandom (p less than 0.01). Of interest is the clear preference for functional vs. nonfunctional V gamma genes (nonfunctional genes being those which carry frameshifts or nonsense mutations but which presumably can still rearrange due to their conserved signal sequences). We discuss the possibilities that this preference may result either from selection of the TRG gamma product at some stage during T cell development or, alternatively, from an intrinsic, antigen-independent polarity in V gamma gene activation.

Germ-line configuration of the T-cell receptor beta-chain gene in B-cell chronic lymphoproliferative disorders which co-express T-cell antigens

In 7 cases of chronic B-cell lymphoproliferative disorders-6 chronic lymphocytic leukaemias and 1 non-Hodgkin lymphoma in leukaemic phase--which co-expressed T-cell markers (CD3, CD2) the clonal origin was investigated at the DNA level. In accordance with the diagnosis, all cases showed a monoclonally rearranged configuration of the immunoglobulin genes. On the contrary, the T-cell receptor beta chain gene always retained a germ-line organization. These findings demonstrate that B-cell chronic lymphoproliferative disorders which co-express T-cell-related markers are truly composed of monoclonal B-cell elements.

Chronic T-cell leukaemias. A variant of T-prolymphocytic leukaemias: morphological, immunological and clinical characterization of 2 cases

In this study we describe 2 patients who appear to suffer from a morphological, cytochemical and clinico-haematological variant of T-prolymphocytic leukaemia (T-PLL). The cells were smaller than typical prolymphocytes, with a regular nucleus containing a smaller and less prominent nucleolus; the alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (AP) cytochemical reactions showed a weaker pattern of positivity in this variant compared to T-PLL. No immunological differences were found between the two conditions with regard to membrane expression and functional behavior of the cells. The clinical course and the outcome of the patients appears to be different: aggressive and rapidly fatal in T-PLL; thus far well-controlled in the T-PLL variant. From a molecular point of view, both cases showed a monoclonal rearrangement of the T-cell receptor beta-chain gene.

Provocative pattern of rearrangements of the genes for the gamma and beta chains of the T-cell receptor in human leukemias

To examine the distribution of rearrangements of the gamma- and beta-chain T-cell receptor (TCR) genes in T- and non-T acute lymphoblastic leukemias (ALLs), and potentially to determine which genes rearrange first in ontogeny, we analyzed high molecular weight DNA from 102 patients with acute leukemia. Rearranged gamma- and beta-chain genes were found in all T-cell ALLs (22/22) examined. Overall, 27% (18/66) of B-lineage ALLs had beta-chain gene rearrangements, and 41% (24/58) had gamma-chain gene rearrangements, but the distribution of rearranged genes varied according to the stage of B-cell differentiation. The gamma-chain genes were rearranged in 11% (1/9) of the B-lineage patients negative for the common acute lymphoblastic leukemia antigen (cALLA) and 50% (23/46) of cALLA+ ALL patients, while the beta-chain genes were not rearranged in any of the 7 cALLA- ALL patients examined but were rearranged in 32% (18/56) of the cALLA+ patients. Neither TCR gene was found to be rearranged in acute nonlymphoid leukemia patients (0/12) or in patients with B-cell (surface immunoglobulin-positive) leukemia (0/3). Of the 44 cALLA+ patients in which a direct comparison of gamma- and beta-chain gene rearrangements could be made, 34% had both genes rearranged, 16% had only gamma-chain gene rearrangements, and the remaining 50% had both genes in the germ-line configuration. beta-Chain rearrangements have not been found in the absence of gamma-chain rearrangements, thus supporting a proposed hierarchy of TCR gene rearrangements. A provocative finding was that only a small percentage (11%) of the patients with cALLA- B precursor cell ALLs had rearranged TCR genes, while 50% of the cALLA+ leukemia patients had at least gamma-chain rearrangement, raising a question as to whether indeed cALLA- cells are precursors to cALLA+ cells. Interestingly, 18% (2/11) of the cytoplasmic immunoglobulin (cIg)-positive cALLA+ (pre-B) ALLs involved TCR gene rearrangements, compared to 60% (21/35) of the cIg-negative cases, suggesting the possibility that the majority of functional B cells are derived from the cALLA+ pool that contains immunoglobulin but not TCR gene rearrangements.

Heterogeneity of large granular lymphocyte proliferations: morphological, immunological and molecular analysis in seven patients

The clinical, morphological, immunological and molecular features of seven patients with a stable picture of chronic granular lymphocytosis, observed over a period of up to 4 years, were studied. Mild splenomegaly was detected in one patient, while lymphoadenopathy and hepatomegaly were absent. Surface marker analysis showed in five patients the common membrane phenotype of granular T-cell lymphocytosis (T3+, T4-, T8+, Leu-7+); of the remaining two, one presented an unusual phenotype (T3+, T4+, T8+) and the other showed a marked positivity with the Leu-11 and M1 monoclonal antibodies, but lacked the T3, T4, T8 antigens. Three cases had a low (less than 30%) expression of the T1 antigen. Functional studies showed that the proliferative response to PHA and the NK function were reduced in four of the seven cases. Molecular analysis, performed in six cases, revealed a monoclonal rearrangement of the T-cell receptor beta-chain gene in three, a polyclonal T-cell configuration in two and a germ-line arrangement in the last. All three monoclonal cases showed a depressed NK activity and two a reduced PHA response. The results of this study document the heterogeneity of granular lymphocyte expansions and suggest that the clonal or reactive nature of these often indolent proliferations, suspected on the basis of immunologic functional studies, may be recognized at the DNA level.

Rearrangements of immunoglobulin and T cell receptor beta and gamma genes are associated with terminal deoxynucleotidyl transferase expression in acute myeloid leukemia

The cell origin of the rare terminal deoxynucleotidyl transferase (TdT)-positive acute myeloid leukemias (AML) was investigated at the molecular level, by examining the configuration of the Ig H (Igh) and L (Ig kappa, Ig lambda) chain gene regions, and of the T cell receptor (TCR) beta and T cell rearranging (TRG) gamma loci. In 8 of the 10 TdT+ AML analyzed (classified as myeloid according to morphological and cytochemical criteria, and to the reactivity with one or more antimyeloid mAbs), a rearrangement of the Igh chain gene was found. In TdT- AML, evidence of an Igh gene reorganization was instead observed only in 2 of the 42 patients studied. Furthermore, evidence of TCR-beta and/or TRG-gamma gene rearrangement was observed in four AML, all of which belonged to the Igh-rearranged TdT+ group. In three cases (one TdT+ and two TdT-), the Ig kappa L chain gene was also in a rearranged position. These findings demonstrate a highly significant correlation between TdT expression and DNA rearrangements at the Igh and TCR chain gene regions and support the view that this enzyme plays an important role in the V-(D)-J recombination machinery. Overall, the genomic configuration, i.e., JH gene rearrangement sometimes coupled to a kappa L chain and TCR gene reorganization, similar to that found in non-T-ALL, suggests that in most cases of TdT+ AML, the neoplastic clone, despite the expression of myeloid-related features, is characterized by cells molecularly committed along the B cell lineage.

Phenotypic, cytogenetic and molecular characterization of a new B-chronic lymphocytic leukaemia (B-CLL) cell line

A lymphoid cell line was established from a patient with B-cell chronic lymphocytic leukaemia (B-CLL) by infecting blood lymphocytes with Epstein-Barr virus (EBV). Immunoglobulin gene rearrangement studies and the presence of a chromosome marker (isochromosome 17q) provided the formal proof that the line has originated from the neoplastic B cells. The morphology and phenotype indicate that the EBV-induced cell line has reached a plasma cell-like stage of differentiation.

Molecular and immunological evidence of B-cell commitment in "null" acute lymphoblastic leukaemia

The DNA configuration of the immunoglobulin (Ig) heavy and light chain genes and the expression of B-cell-related markers were evaluated in 13 cases of non-T, non-B, non-common ("null") acute lymphoblastic leukaemia (ALL). A rearrangement of the Ig heavy-chain gene was found in all cases studied; in 5 of these a structural reorganization of the kappa or lambda light chain gene was also demonstrated. Leukaemic cells from 10 of the 13 cases analysed showed one or more B-cell antigens, the expression of which followed a sequential order of presentation (OKB2, B4, BA-1, B1). The B-cell commitment was confirmed by means of a sensitive immunoperoxidase assay which revealed a weak expression of the common ALL (cALL) antigen in 7/10 cases tested, which were all cALL-negative by conventional immunofluorescence techniques. These findings suggest that in "null" ALL the neoplastic cells show molecular and immunological evidence of B-cell differentiation and that most cases may indeed be characterized by "early" cALL with a very low density expression of the cALL antigen. This was further documented in one case in which the expression of the cALL antigen (and of other B-cell markers) could be induced after exposure to 12-O-tetradecanoylphorbol-13-acetate (TPA). The presence in a few cases of myeloid features, particularly when the cALL antigen could not be demonstrated by the immunoperoxidase assay, suggests that the leukaemic process may sometimes involve a very early progenitor cell capable of both lymphoid and myeloid phenotypic differentiation. The heterogeneity of "null" ALL documented by this study may help to explain the variable clinical course and prognosis of these patients.

Lineage-related polypeptide markers in acute lymphoblastic leukemia detected by two-dimensional gel electrophoresis

We have utilized two-dimensional polyacrylamide gel electrophoresis, coupled with ultrasensitive silver staining, to identify lineage-related polypeptide markers in lymphoblasts from children with acute lymphoblastic leukemia. Twelve polypeptides were detected that could distinguish between the major subgroups of acute lymphoblastic leukemia. These included a new marker for common acute lymphoblastic leukemia and markers for cells of B and T lineages. Analysis of the two-dimensional patterns also allowed the tentative identification of T-cell lineage in two cases with an otherwise undifferentiated non-T-cell non-B-cell phenotype. Two-dimensional electrophoresis thus provides a powerful tool for the delineation of the cell of origin in leukemia.

Immunological typing of acute lymphoblastic leukemia: concurrent analysis by flow cytofluorometry and immunocytology

For 60 cases of acute lymphoblastic leukemia (ALL) immunological typing was done concurrently by the avidin-biotin-peroxidase method using cytocentrifuged smears and by flow cytofluorometry for the study of surface antigens. The use of a large panel of antibodies detecting differentiation antigens allowed us to sub-classify 57/60 cases as 43 B-lineage ALLs and 14 T-lineage ALLs. The two types of ALL can be accurately distinguished by the expression of the antigens recognized by the antibodies of the clusters of differentiation CD19 (B4) and CD7 (Leu 9). Almost perfect agreement was obtained between the results of the two methods for antigens DR, CD10 (cALLA;J5) and CD7. A number of discordances were observed with other antigens [CD19 (B4), CD20 (B1), CD22 (To15), CD1 (T6), CD2 (T11), CD4 (T4), CD8 (T8), CD3 (T3), T9, T10]. In spite of these discordances, the avidin-biotin-peroxidase method can predict the lineage involved in most ALLs with a high degree of reliability. Nevertheless, for weakly expressed surface antigens (such as B4 and B1) the immunocytological method is less sensitive than flow cytofluorometry and can only approximately determine the stage of differentiation of neoplastic cells. Furthermore, the existence of cases which are at the same time negative with flow cytofluorometry and positive with immunocytology is consistent with the intracytoplasmic expression of certain differentiation antigens. Thus in the course of lymphoid differentiation, intra-cytoplasmic expression of T3, To15 and possibly J5 precedes their expression at the cell surface.

Multimarker phenotypic characterization of adult and childhood acute lymphoblastic leukaemia: an Italian multicentre study

A multicentre phenotypic study was carried out in Italy combining conventional immunological techniques with monoclonal antibody (MoAb) analysis in 190 cases of adult and childhood acute lymphoblastic leukaemia (ALL), in an attempt to define better the lineage relationship of the neoplastic cells. Of the 140 children evaluated, 79.3% expressed the common ALL (cALL) antigen (all analyses performed by MoAb), 11.4% were T-ALL and 9.3% were non-T, non-B, non-common ('null') ALL. The proportion of adult cALL cases was slightly lower (64% of the 50 cases studied) than that of childhood ALL, whilst the incidence of T-ALL was significantly higher in adults than in children (26% v. 11.4%, P less than 0.05). Because of the high proportion of cALL cases, the incidence of 'null' ALL in adult patients was similar (10%) to that of children, and lower than previously reported. The recognition of early pre-T-ALL cases (T1+, RFT2+, T10+, T6-, T11-, E-) contributed to the overall low proportion of 'null' ALL; prior to the use of MoAb, such cases would probably have been classified as undifferentiated acute leukaemia or 'null' ALL. The search for B-cell-related markers showed that the incidence of pre-B-ALL cases (cytoplasmic immunoglobulin positive cases) was similar in adults and in children (25.6% and 32%, respectively). Furthermore, the great majority of cases studied expressed the BA-1 antigen (92.8% of adults and 79% of children), whilst the BA-2 antigen was found in 53% of cases (tested only in children), confirming a hierarchy in the expression of B-cell related markers in cALL: BA-1, BA-2, CyIg. Several of the 'null' cases also expressed the BA-1 antigen on a variable proportion of cells, pointing to a possible B-cell origin of the blasts. This multicentre study shows that both in adult and in childhood ALL the combined use of conventional immunological markers and of a panel of MoAb allows identification of the cell lineage of the great majority of cases, thus reducing the number of 'null' ALL. Furthermore, these findings suggest that practically all cases of ALL belong either to the T or to the B cell compartment and that the neoplastic cells appear blocked at different levels along the lymphoid differentiation pathway.